Wednesday, August 10, 2016

In a previous life I was around airplanes a lot. I spent 6 years going to college and flight school, and I've got couple of green plastic cards with a bunch of acronyms on them to prove it. These days however I'm known as a PWOP - a "Pilot WithOut a Plane" as the industry just didn't allow me to do the things I wanted to do life. It's fine though, I don't regret the choices I made one bit.. and a big reason is a number of the things I learned from Flight School have stuck with me in my non-aviation related fields, and have served me quite well. Probably the biggest one is the concept of Situational Awareness.

As best I can tell, there is no one definition for what Situational Awareness is. The best explanation I can find comes from Endsley in a meeting on Human Factors in Aviation from 1988. He defined the following:

Situational Awareness is:

The Perception of the elements in the environment within a volume of time and space,

The comprehension of their meaning and,

The projection of their status in their near future.

To try and turn this into something more applicable to those of us using the English Language, if you posses SA, you know where relevant things are around you, you know why they are the way they are, how they got there, where they're going, and what this means to you and others.

At this point I'm sure you're wondering WTF I'm going on about. This is a radio blog after all... well, Situational Awareness is a very applicable skill in radio. Let's take HF for example... depending on where the sun is in relative position to you on our planet, propagation to someone you want to talk to may be affected. You're likely not going to do too well trying to nab that DX contact a few thousand miles away on 10 meters when both you and him are in the dark. You would likely aim for when you both have some sort of F layer excitation occurring and the frequency you want is being reflected back down to earth via the atmosphere, ie, when the sun is shining. Recognizing this fact and acting upon it is an example of Situational Awareness, albeit one that only requires rote understanding of HF propagation mechanics, and as much time as you need to process the idea with your gray matter.

Now consider something like a LEO Satellite pass. You will have visibility to a typical SO-50 pass for about 11-13 minutes, depending on a whole host of factors. The pass will always start generally to the north or south, and traverse across the sky towards the south or north (respect to ascending/descending passes). Now consider you want to work someone on said Satellite that is south of you. That station has their own visibility path, relative to their position on the globe as well. Your station and their station will have what is known as a 'footprint' or a 'window' to work each other, where the satellite is in view of both of your stations. If you're close together, say only a few hundred miles apart, that window will be very long, as your view of the satellite will be similar to what that other person's view is too. If your stations are far apart, say a few thousand miles, the overlap will be shorter.. sometimes MUCH shorter. Now consider something like a rare DX station, that lots of people are going to want to make contact with. Calculate up all these different windows from Station A to Station DX and some people are going to have a lot of time to make the contact, some people are going to have a short amount of time, and it's all going to be relative to their position on the globe, and their view of the bird.

So, where am I going with all of this. If you have superior Situational Awareness skills, in your head you're probably recognizing all the elements (stations) in the environment (satellite view) within a volume of time (window) and space (locations of all of this). You are comprehending their meaning (some stations will have more time than others) and projecting their status (when is the 'best' time to call for each) in the near future (when should I call). Head asplode yet?

Let's try this as an exercise. You have a DX station in the country of Sint Maarten. There is a descending SO50 pass that looks something like this at AOS:

Like this at TCA:

And This at LOS:

And of course, all sorts of incremental variations of the footprint across the path of the bird.

Let's say you've got two stations that want to make contact with PJ7, one of them is in Iowa, the other is in Florida. The distance between IA and PJ7 is significant, so the window is going to be small. The station in FL on the other-hand is relatively close to PJ7 (in satellite terms) so the window is going to be nice and long. When AOS occurs in PJ7, should the Florida station immediately key up his/her mic and make contact? There's no rule or law against it, that person certainly can.. but SHOULD they? Consider the IA station now, when PJ7 goes AOS, should THEY key up there mic? Probably, but in the realm of situational awareness, you should KNOW. Maybe there's a station in Manitoba that also wants to work PJ7 as well, if there is, then IA should standby, as MB will have even less time than IA to make the contact. Every time you add in a new station, you have to add in a new element into your SA calculations. Let's consider adding Illinois, Ohio, Texas, Arkansas and North Carolina to the mix. Now consider the power and ears of each station - as some stations can obviously work to lower elevations than others, and some stations can turn up their transmit to 11 and crush everyone else. Consider a special circumstance like a newer operator not used to rapid fire Satellite QSO exchanges.. Consider that the DX station may not have the best operating environment and may not be on the Satellite right at their AOS. Consider interference from non-satellite users operating outside the band plans... and consider this, consider that, and on and on and on.. Every time there's something new to consider, it's a new element in your Situational Awareness calculations that impact your decision of when to hit that precious PTT button.

So where does this leave us in the real world? Well, that depends. On some passes, on some birds - what I described happens. All the operators have good situational awareness, make time for other stations with small footprints, abide by the golden rule of "If you can't hear the bird, don't transmit" and generally are aware of what's happening. These passes are great, and DO happen. A few days ago I worked AO-85 from here in Arkansas, and had a 2.7° TCA elevation towards the Northeast. That's a pretty stinking low pass.. I managed to work N9IP/VO1 from a rare grid in Newfoundland on this pass, and it was a blast. What is interesting though, was that there were a bunch of stations on the pass, with a much bigger footprint than me, that held tight. They knew I was there, they knew I'm a portable operator, they knew I was hunting for Steve. They stood by, let me complete the QSO while I had a window, and then called N9IP after my window had expired, when they still had plenty of elevation. It was a beautiful thing. Everyone got the rare grid, no one was upset, everyone was polite, and most importantly - everyone had great situational awareness. Does this always happen? Hardly... most of the time everyone adopts a 'HAVE TO THROW CALL OUT RAWR RAWR RAWR' mentality, and 1 or 2 might get thru, and the rest are shut out. I understand, it happens.. but it shouldn't have too. In a later post I fully plan on discussing my own personal rules for satellite operating and how it can lead to a more enjoyable hobby, but I've written enough for now. Just remember this whole idea about Situational Awareness - it will make the radio world (and especially on Satellite) a better place.

Monday, August 1, 2016

The #1 question I get asked with regards to Ham Radio is "What kind of equipment do you use to operate on the Satellites?" - worded in about 47 different possibilities. I plan to make this post the one stop shop for my current AMSAT Station configuration, and I'll update it as needed if any life changing modifications are required.

So, how do I work Satellites? It comes to 4 things really.

1: Antenna:

I start with the Antenna because it paramount to successful operation on the birds. Yea Yea, you've heard it all before 'the antenna is the biggest part of your station' yada yada.. Well, I mean it. If your antenna system sucks, then don't even bother trying to get on the birds. Really. Seriously. Just go away. You'll end up transmitting in the blind and being deaf as a post and ruining the bird for everyone else. Whatever antenna you decide to use it needs to have some GAIN on it. I personally use two different varieties of Arrow Antennae (a small version and a big version.. more about that in a later post) for my operations and they work fantastically. You also may see me playing around 'cheap yagis' from time to time.. These are home-brewed gain antennae made out of plywood and welding rod. They also work pretty good. Any other type of gain antenna will work, but you're dealing with very weak signals, mostly < 1W, and so gain is absolutely required. Anyone who tells you it isn't, isn't a very successful operator.

2. Good Coax:

OK, so that picture isn't actually the coax I use, but it's an example of a station owned by a guy who get's it, and thus, makes the point more dramatic. Use the best coax you can afford, and is practical for your station. In that picture, 7/8th hardline works... In my station, I use 2x 8' pieces of Times LMR-240. I almost emphasize coax as much as I emphasize using the proper antenna, because there's no way you can cause more damage to your ability to hear than using cheap lossy coax. Make sure to have the proper terminators on each end, that are high quality silver Amphenols, and make sure the coax is in good condition. Test it regularly to make sure it's as close to 0db loss as possible. I have gotten by with RG58 and RG8X in the past, but only on very short runs (like < 12") and usually only then for a novelty. When dealing with VHF/UHF frequencies, anything shy of LMR just doesn't cut it if you want to be a serious op.

3. Rig

Now we're getting into some places where there is room for interpretation. At it's heart, you need a rig (or rigs) capable of operating on the band and mode the Satellite is transmitting and receiving on. Simple enough right? At the moment my rig of choice for Satellite operation is my Icom 821h. It is a 2M/70cm dual VFO, full duplex, all mode rig. It has some nice features like VFO lock, RIT and some other things that make it nice for bird operation, plus it will do anywhere from 2W-30W on 70cm and 5W-40W on 2m - which is more than enough to get into the birds with a strong signal to overcome QRM when needed, but not enough I have to do a RF field study when running at modest levels (Or using AO-7(B) you QRO numpties). You will also see me using my 857d on occasion, and pairing it with a random HT. Sometimes if I'm doing just the FM birds, I'll be using my FT2900 in the Jeep as one side of the equation. Sometimes you'll see me using my FunCube Dongle Pro+ to receive SDR style. There's really a lot of choices here. Some work better than others, but you can make a whole lot of things work if you try.

4. Accessories

Lots of different options here - I'll just go over a few that make my life easier. First - a headset. I use a Heil Pro Micro. When one hand is holding your antenna, and the other is trying to adjust the dial and write stuff down, having a headset is practically a necessity. Also in this picture, you'll see a battery. This is a personal preference thing, and you can read more about them in my Battery Powered blog entry, but I like the LiFePo4 battery packs for normal operation.

You'll also see in this picture a few more extras. There's Heil Audio footswitch that is used as my PTT button. See above necessity to have 4 hands to see why this is nice. I've also got a little cheap foldable table I bought at Home Depot to put everything on when I'm out in the field... It's the perfect height and perfect size. Finally I've got a big tub that all my gear goes into for easy packing. I'll almost always have pencil and paper.. sometimes I use a voice recorder, sometimes I'll have an external speaker on a tripod and a camera too.. it all just depends on what I'm trying to accomplish with that pass.

Howdy!

My name is Dave, and I'm a Ham radio operator here in Central Arkansas. I got licensed back in May of 2014, but I've discovered some really fun things you can do with radios since then. My specialty is working Amateur Radio Satellites, but you'll find me doing mountain-top VHF/UHF work, and operating backpack portable as I climb many of the great peaks here in the Ouachita and Ozark mountains. I practically never operate from my house, as I've got better things to do when I'm there, but while I'm out and about, a radio is never far away.